Config: Override configuration with environment variables not working in kubernetes

### What happened? Hi, i am trying to implement [security features](https://grafana.com/docs/grafana/latest/setup-grafana/configure-security/) in my grafana that is deployed in our kubernetes cluster, using one of the latest image, `grafana/grafana-oss:12.2.0-17142428006` ### What did you expect to happen? Was doing `Limit IP addresses/hostnames for data source URL` which requires us to set [data_source_proxy_whitelist](https://grafana.com/docs/grafana/latest/setup-grafana/configure-grafana/#data_source_proxy_whitelist). So i followed the naming convention and expose the following in the environment variables in my kubernetes yaml manifest for grafana deployment. Exposed ```yaml env: - name: GF_SECURITY_DATA_SOURCE_PROXY_WHITELIST value: "prometheus:9090" ``` But i am still able to query other data source from grafana after applying this configuration. Was wondering if, the environment variable convention was wrong, so went ahead to try the following, and my admin user is indeed now `test` instead of the standard `admin`. This meant that this method of exposing the env variable works. ```yaml env: - name: GF_SECURITY_ADMIN_USER value: test ``` Decided to went one step further and edit directly the grafana.ini file, and setting the `data_source_proxy_whitelist=prometheus:9090` field directly, before starting the grafana server. Also, doesn't work. So question is, am i configuring something wrong here? or am i missing something. Help needed, thank you! ### Did this work before? Was on 2025-feb version of grafana-oss version, wasn't working so decided to upgrade to `grafana/grafana-oss:12.2.0-17142428006`, still dint work ### How do we reproduce it? 1. Deploy grafana deployment manifest on kubernetes with environment variable GF_SECURITY_DATA_SOURCE_PROXY_WHITELIST set to the dedicated data source. 2. Go to grafana UI and add datasource, check if other datasources is query-able ### Is the bug ins…